Synthesis and structural characterization of four di-chlorido-bis-(cyclo-propyl-alkynyl-amidine)-metal complexes

Deliberate hydrolysis of lithium cyclo-propyl-alkynylamidinates, Li[c-C₃H₅-C≡C(NR')₂] [R' = Pr, Cy = cyclo-hex-yl)], afforded the hitherto unknown neutral cyclo-propyl-alkynyl-amidine derivatives c-C₃H₅-C≡C-C(NR')(NHR') [R' = Pr (1), Cy (2)]. Subsequent reactions of 1 or 2 with metal(II) chlorides, MCl₂ (M = Mn, Fe, Co), provided the title complexes di-chlorido-bis-(3-cyclo-propyl-N,N'-diisopropyl-prop-2-ynamidine)-manganese(II), [MnCl₂(C₁₂H₂₀N₂)₂], (3), di-chlorido-bis-(3-cyclo-propyl-N,N'-diisopropyl-prop-2-ynamidine)-iron(II), [FeCl₂(C₁₂H₂₀N₂)₂], (4), di-chlorido-bis-(N,N'-di-cyclo-hexyl-3-cyclo-propyl-prop-2-ynamidine)-iron(II), [FeCl₂(C₁₈H₂₈N₂)₂], (5), and di-chlorido-bis-(N,N'-di-cyclo-hexyl-3-cyclo-propyl-prop-2-ynamidine)-cobalt(II), [CoCl₂(C₁₈H₂₈N₂)₂], (6), or more generally MCl₂[c-C₃H₅-C≡C-C(NR')(NHR')]₂ [R' = Pr, M = Mn (3), Fe (4); R' = Cy, M = Fe (5), Co (6)] in moderate yields (30-39%). Besides their spectroscopic data (IR and MS) and elemental analyses, all complexes 3-6 were structurally characterized. The two isopropyl-substituted complexes 3 and 4 are isotypic, and so are the cyclo-hexyl-substituted complexes 5 and 6. In all cases, the central metal atom is coordinated by two Cl atoms and two N atoms in a distorted-tetra-hedral fashion, and the structure is supported by intra-molecular N-H⋯Cl hydrogen bonds.